Do a malware check with some malware scanning programs on the Windows computer.<br /> You need to scan with all programs because each program detects different malware.<br /> Make sure that you update each program to get the latest version of their databases before doing a scan.<br /><br /> *http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware *http://www.superantispyware.com/ - SuperAntispyware *http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page *http://www.safer-networking.org/en/index.html - Spybot Search & Destroy *http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free If using the above listed scanners does not fix it or if you are blocked from installing those scanners then ask advice on one of the forums that specialize in malware removal mentioned in the <i>Popups_not_blocked</i> article. See also: *"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked